US2337391A - Haircutting device - Google Patents

Description

ec. 2L i943. A. HoRowlTz ET AL 2,337,391 HAIR CUTTING DEVICE Filed March 5, 1940 Patented Dec. 21, 1943 HAIRCUTTING DEVICE Alexandre Horowitz and Alexis hoven, Netherlands, assigno van Dam, Eindby mesne assignments, to Hartford National Bank and Trust Company, Hartford, Conn., Application March 5, 1940, Serial No.

as trustee In Germany February 21, 1939 claims. (ci. so-ia) Our invention relates to hair-cutting devices, particularly dry electric razors, having a cutting or shear plate and a rotatable cutter which is usually electrically driven,

Although not limited thereto, our invention is particularly adapted for use in hair-.cutting de vices of the type described in our co-pending U. S. patent application Ser. No. 276,746 led May 31, 1939.

In devices of the above type the cutter gener-A ally runs in a groove in the shear plate and is confined to a fixed path. More particularly, the cutter may snugly' fit into the groove and be guided by the walls thereof, or may be exactly centered in the groove, for instance by being accurately journalled on the shaft ofthe cutter or by being mounted on a pin which is accurately journalled in the cutting plate. We have found that when such devices have been in service for some time. grooves may be cut into one or both of the active surfaces of the cutter and shear plate. As a result the cutting action is deleteriously affected and in addition the shear plate may be heated due to the high friction produced by the roughened surfaces, which is particularly disadvantageous because the shear plate comes in contact with the skin during operation. Furthermore, the friction of the roughened surfaces increases the load on the motor and slows down the same.

The main object of our invention is to overcome the above difficulties and for this purpose we make the groove slightly wider than the cutter and so mount the cutter that it will be guided solely by the walls of the groove. cutter has a small clearance,` for instance about 0.2 mm., with the walls of the groove and is free to move over the entire cutting surface thereof.

The radial movement of the cutter is limited only by the Walls of the groove and therefore the cutter will move with a combined radial and circular motion over the entire surface of the plate. Consequently. there will be no grooving or erosionof the active surfaces and shear plate. Furthermore, after the device has been operated for a short time the active surfaces take on a high polish which reduces the friction and consequently the heating of the shear plate and the load on the motor. As a result the speed of the motor increases which improves the cutting action, and shorter cutting of the hair is obtained.

We prefer that the surfaces of the groove which guide the cutter, as well as the corresponding surfaces of the cutter, make an angle of about Thus, the.

of the cutter j with the active surface of the groove, so as to obtain an accurate guiding.

In one embodiment of the invention we resiliently mount the cutter and make the depth ofv erence to the accompanying drawing in which the single figure is a sectionized side view of a portion of an electric dry razor embodying the invention.

In the drawing, the reference numeral 9 indicates a housingof insulating material, such as Bakelite, in which's located an electric motor having a shaft 1 provided at its end with a bore and a diametrical slot 6. Secured to the end of housing 9 by means of a screw collar 20 of Bakelite" is a cup-shaped metal shear plate 2l.

Shear plate 2 l is provided with a central cavity 22 and a plurality of radially-extending narrow slits 2 which extend through the annular end portion. 'Ihe inner part of the annular portion is provided with an annular groove 25 having a width I2.

A hollow member I of insulating material has two projections Y two projections 23. A compression spring 8 has one end bearing on shaft 'l and its other end bearing on the member 4 to forcethe latter upward. The projections 23 t into clearance holes in a cutter 3 having two engage 'the bottom surface of groove 25.

The spring 8! serves to press the cutting edges Il against the shear plate 2| and a metal member i0 screwed into housing 9 serves to limit the cutter 3 and for this purpose has its upper surface spaced a distance I1 from the lower surface of the cutter.

According to the invention the groove 25, which determines the active cutting surface, is so proportioned that the cutter 3 has a small play of, for example, 0.2 mm., in the radial direction. For this Purpose the width I2 ofthe groove 25 is made about 0.2 mm. greater centered exclusively I5 of the groove 25,

The movable mounting of member 4 on shaft l cutting edges il which and within member I permits free radial movement of the cutter 3 within the entire groove 25 so that the bottom surface of the groove is automatically maintained smooth, and heating. erosion or grooving of the cutting edge of the cutter and the bottom surface of the groove 25 is avoided.

To obtain an exact boundary of the active bottom surface of groove 25, it is advisable that the walls I4 and I5 as well as the cooperating end surfaces of the cutter 3 extend perpendicular to the active bottom surface of groove 25.

The depth I6 of groove 25 is preferably made greater than the distance the cutter 3 can move in the axial direction, i. e. distance I1. This prevents the cutter 3 from leaving groove II under any condition, even if the motor is removed.

As shown the shear plate I is stationary, but it may also be movable, as described in our copending U. S. patent application S. N. 303,290, iiled November 7, 1939, now U. S. Patent No. 2,283,834, issued May 19, 1942.

Although we have reference to specic examples and applications, we do not desire to be limited thereto because obvious modifications will present themselves to one skilled in the art..

What we claim is:

1. In a hair-cutting device, a shear plate provided with a groove having an active cutting surface and guiding surfaces, a member having a cutting portion running within said groove, said cutting portion having a, clearance of the order of 0.2 mm. with said guiding surfaces of the groove, a driving means, and a coupler member loosely connecting said cutter member to said driving means allowing free movement of the cutter member between said guiding surfaces. n

2. In a hair-cutting device, a shear plate provided with an annular groove having an active cutting surface and guiding surfaces, a member having a cutting portion running within said groove and being rotatably driven, said cutting portion having a width of the order of 0.2 mm. less than the distance between said guiding surfaces, a driving means, and a, coupler member loosely connecting said cutter member to said described our invention with driving means allowing free radial movement of the cutting portion between the guiding surfaces of the grooves.

3. In a hair-cutting device, a shear plate provided with a groove having an active cutting surface and guiding surfaces substantially perpendicular thereto, amember having a cutting portion running within said groove and having surfaces parallel to said guiding surfaces the distance between said latter surfaces being of the order 0f 0.2 mm. less than the distance between the guiding surfaces, a driving means, and a coupler member loosely connecting said cutter member to said driving means allowing free movement of the cutting portion between the guiding surfaces.

4. In a hair-cutting device, a shear plate provided with a groove having an active cutting surface and guiding surfaces, a member having a cutting portion running within said groove, said cutting portion having a clearance of the order of 0.2 mm., withsaid guiding surfaces, a driving means, and a coupler member loosely connecting said cutter member to said driving means allowing free movement of the cutter member between the guiding surfaces, resilient means pressing thecutting portion against the active surface of the shear plate while permitting movement in a direction perpendicular thereto, and means to restrict said movement to a distance less than the depth of the groove.

5. In a hair-cutting device, a shear plate provided with an annular groove having a radially extending active cutting surface and guiding surfaces perpendicular to said cutting surface, a rotatable member having a cutting portion running within said groove engaging the cutting surface thereof and having -a radial clearance of the order of 0.2 mm. with said guiding surfaces, a driving means, and a coupler member loosely connecting said cutter member to said driving means allowing free radial movement of said cutting portionwithin the annular groove limited by the said guiding surfaces thereof.

ALEXANDRE HOROWITZ. ALEXIS VAN DAM.

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